obsidian-tc: Declined human-in-the-loop confirmations can permit destructive calls over HTTP

### Summary On a Streamable HTTP deployment with `auth.jwtSecret` configured, serving a 2026-07-28-era client that declared `elicitation.form` support, a call to a dispatch-gated tool (`destructive: true`, or a scope with an HITL floor) that was offered an `inputRequired` confirmation could still complete after the human declined, cancelled, or the elicitation response was omitted or malformed, provided the client echoed the validly bound `requestState` on resubmission. The server trusted an authentic, call-bound state as proof of approval; the state is minted before the elicitation leg is asked, so it proves only that the resubmission belongs to the same call. ### Details Reproduced directly: a `destructive: true` tool call, offered `inputRequired`, answered with `{action: "decline"}` on the `elicitation/create` leg, still wrote. Present since the 2026-07-28 round trip shipped in v1.13.0 (THE-583). Only dispatch-gated tools were reachable; the sixteen handler-side conditionally gated tools (`write_note` overwrite, `move_note`, and others) did not read the elicitation state on the modern wire at all, so they neither let a decline nor an approval through. ### Impact A client that echoes state after a decline can execute destructive vault operations (delete, cross-folder move, frontmatter replace, link rewrite) that the human explicitly refused. The precondition is a compliant client behaving incorrectly or a client under an attacker's control; the human's refusal is not enforced by the server. ### Patches Fixed in 1.31.4: the server now also requires the confirm leg's own response (`inputResponse`) to be `{action: "accept", content: {approve: true}}` before trusting the echoed state. A declined, cancelled or not-approved round renders the ordinary `elicit_required` error and is never offered a second round for the same declined confirmation. The same release adds server-initiated in-band confirmation on stdio (legacy era), so stdio agents no longer need to mint `elicit_token` themselves. ### Not addressed A malicious or non-compliant client can still answer its own `elicitation/create` leg with an approval regardless of what the human said. The server cannot verify that the client rendered the form or that a human saw it; this is inherent to the client-driven half of the 2026-07-28 protocol. The legacy shim, where the server sends and owns the leg, does not share this gap. ### Workarounds Run affected deployments over stdio, or leave `auth.jwtSecret` unset so the `requestState` codec (and therefore `inputRequired`) is never offered; both fall back to the CLI `elicit_token` path. ### Credit Reported in GH #967; found and closed under THE-1106 (PR #969); the residual is documented in SECURITY.md. ### References - PR #969, GH #967, CHANGELOG `## [1.31.4] ### Security` - `packages/server/src/mcp/server.ts` (`tools/call` handler), `packages/server/src/vault/hitl.ts`

Source published

23 Oct 2026 17:30:10 UTC

Source modified

23 Oct 2026 17:45:03 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Publisher rating · HIGH